kern_clock.c revision 1.143
1 /* $NetBSD: kern_clock.c,v 1.143 2020/12/05 18:17:01 thorpej Exp $ */ 2 3 /*- 4 * Copyright (c) 2000, 2004, 2006, 2007, 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center. 10 * This code is derived from software contributed to The NetBSD Foundation 11 * by Charles M. Hannum. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 23 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 24 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 25 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 26 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 27 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 28 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 29 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 30 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 31 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 32 * POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 /*- 36 * Copyright (c) 1982, 1986, 1991, 1993 37 * The Regents of the University of California. All rights reserved. 38 * (c) UNIX System Laboratories, Inc. 39 * All or some portions of this file are derived from material licensed 40 * to the University of California by American Telephone and Telegraph 41 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 42 * the permission of UNIX System Laboratories, Inc. 43 * 44 * Redistribution and use in source and binary forms, with or without 45 * modification, are permitted provided that the following conditions 46 * are met: 47 * 1. Redistributions of source code must retain the above copyright 48 * notice, this list of conditions and the following disclaimer. 49 * 2. Redistributions in binary form must reproduce the above copyright 50 * notice, this list of conditions and the following disclaimer in the 51 * documentation and/or other materials provided with the distribution. 52 * 3. Neither the name of the University nor the names of its contributors 53 * may be used to endorse or promote products derived from this software 54 * without specific prior written permission. 55 * 56 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 57 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 58 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 59 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 60 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 61 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 62 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 63 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 64 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 65 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 66 * SUCH DAMAGE. 67 * 68 * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 69 */ 70 71 #include <sys/cdefs.h> 72 __KERNEL_RCSID(0, "$NetBSD: kern_clock.c,v 1.143 2020/12/05 18:17:01 thorpej Exp $"); 73 74 #ifdef _KERNEL_OPT 75 #include "opt_dtrace.h" 76 #include "opt_gprof.h" 77 #endif 78 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/callout.h> 82 #include <sys/kernel.h> 83 #include <sys/proc.h> 84 #include <sys/resourcevar.h> 85 #include <sys/signalvar.h> 86 #include <sys/sysctl.h> 87 #include <sys/timex.h> 88 #include <sys/sched.h> 89 #include <sys/time.h> 90 #include <sys/timetc.h> 91 #include <sys/cpu.h> 92 #include <sys/atomic.h> 93 94 #ifdef GPROF 95 #include <sys/gmon.h> 96 #endif 97 98 #ifdef KDTRACE_HOOKS 99 #include <sys/dtrace_bsd.h> 100 #include <sys/cpu.h> 101 102 cyclic_clock_func_t cyclic_clock_func[MAXCPUS]; 103 #endif 104 105 static int sysctl_kern_clockrate(SYSCTLFN_PROTO); 106 107 /* 108 * Clock handling routines. 109 * 110 * This code is written to operate with two timers that run independently of 111 * each other. The main clock, running hz times per second, is used to keep 112 * track of real time. The second timer handles kernel and user profiling, 113 * and does resource use estimation. If the second timer is programmable, 114 * it is randomized to avoid aliasing between the two clocks. For example, 115 * the randomization prevents an adversary from always giving up the CPU 116 * just before its quantum expires. Otherwise, it would never accumulate 117 * CPU ticks. The mean frequency of the second timer is stathz. 118 * 119 * If no second timer exists, stathz will be zero; in this case we drive 120 * profiling and statistics off the main clock. This WILL NOT be accurate; 121 * do not do it unless absolutely necessary. 122 * 123 * The statistics clock may (or may not) be run at a higher rate while 124 * profiling. This profile clock runs at profhz. We require that profhz 125 * be an integral multiple of stathz. 126 * 127 * If the statistics clock is running fast, it must be divided by the ratio 128 * profhz/stathz for statistics. (For profiling, every tick counts.) 129 */ 130 131 int stathz; 132 int profhz; 133 int profsrc; 134 int schedhz; 135 int profprocs; 136 int hardclock_ticks; 137 static int hardscheddiv; /* hard => sched divider (used if schedhz == 0) */ 138 static int psdiv; /* prof => stat divider */ 139 int psratio; /* ratio: prof / stat */ 140 141 static u_int get_intr_timecount(struct timecounter *); 142 143 static struct timecounter intr_timecounter = { 144 .tc_get_timecount = get_intr_timecount, 145 .tc_poll_pps = NULL, 146 .tc_counter_mask = ~0u, 147 .tc_frequency = 0, 148 .tc_name = "clockinterrupt", 149 /* quality - minimum implementation level for a clock */ 150 .tc_quality = 0, 151 .tc_priv = NULL, 152 }; 153 154 static u_int 155 get_intr_timecount(struct timecounter *tc) 156 { 157 158 return (u_int)getticks(); 159 } 160 161 int 162 getticks(void) 163 { 164 return atomic_load_relaxed(&hardclock_ticks); 165 } 166 167 /* 168 * Initialize clock frequencies and start both clocks running. 169 */ 170 void 171 initclocks(void) 172 { 173 static struct sysctllog *clog; 174 int i; 175 176 /* 177 * Set divisors to 1 (normal case) and let the machine-specific 178 * code do its bit. 179 */ 180 psdiv = 1; 181 182 /* 183 * Call cpu_initclocks() before registering the default 184 * timecounter, in case it needs to adjust hz. 185 */ 186 const int old_hz = hz; 187 cpu_initclocks(); 188 if (old_hz != hz) { 189 tick = 1000000 / hz; 190 tickadj = (240000 / (60 * hz)) ? (240000 / (60 * hz)) : 1; 191 } 192 193 /* 194 * provide minimum default time counter 195 * will only run at interrupt resolution 196 */ 197 intr_timecounter.tc_frequency = hz; 198 tc_init(&intr_timecounter); 199 200 /* 201 * Compute profhz and stathz, fix profhz if needed. 202 */ 203 i = stathz ? stathz : hz; 204 if (profhz == 0) 205 profhz = i; 206 psratio = profhz / i; 207 if (schedhz == 0) { 208 /* 16Hz is best */ 209 hardscheddiv = hz / 16; 210 if (hardscheddiv <= 0) 211 panic("hardscheddiv"); 212 } 213 214 sysctl_createv(&clog, 0, NULL, NULL, 215 CTLFLAG_PERMANENT, 216 CTLTYPE_STRUCT, "clockrate", 217 SYSCTL_DESCR("Kernel clock rates"), 218 sysctl_kern_clockrate, 0, NULL, 219 sizeof(struct clockinfo), 220 CTL_KERN, KERN_CLOCKRATE, CTL_EOL); 221 sysctl_createv(&clog, 0, NULL, NULL, 222 CTLFLAG_PERMANENT, 223 CTLTYPE_INT, "hardclock_ticks", 224 SYSCTL_DESCR("Number of hardclock ticks"), 225 NULL, 0, &hardclock_ticks, sizeof(hardclock_ticks), 226 CTL_KERN, KERN_HARDCLOCK_TICKS, CTL_EOL); 227 } 228 229 /* 230 * The real-time timer, interrupting hz times per second. 231 */ 232 void 233 hardclock(struct clockframe *frame) 234 { 235 struct lwp *l; 236 struct cpu_info *ci; 237 238 ci = curcpu(); 239 l = ci->ci_onproc; 240 241 ptimer_tick(l, CLKF_USERMODE(frame)); 242 243 /* 244 * If no separate statistics clock is available, run it from here. 245 */ 246 if (stathz == 0) 247 statclock(frame); 248 /* 249 * If no separate schedclock is provided, call it here 250 * at about 16 Hz. 251 */ 252 if (schedhz == 0) { 253 if ((int)(--ci->ci_schedstate.spc_schedticks) <= 0) { 254 schedclock(l); 255 ci->ci_schedstate.spc_schedticks = hardscheddiv; 256 } 257 } 258 if ((--ci->ci_schedstate.spc_ticks) <= 0) 259 sched_tick(ci); 260 261 if (CPU_IS_PRIMARY(ci)) { 262 atomic_store_relaxed(&hardclock_ticks, 263 atomic_load_relaxed(&hardclock_ticks) + 1); 264 tc_ticktock(); 265 } 266 267 /* 268 * Update real-time timeout queue. 269 */ 270 callout_hardclock(); 271 } 272 273 /* 274 * Start profiling on a process. 275 * 276 * Kernel profiling passes proc0 which never exits and hence 277 * keeps the profile clock running constantly. 278 */ 279 void 280 startprofclock(struct proc *p) 281 { 282 283 KASSERT(mutex_owned(&p->p_stmutex)); 284 285 if ((p->p_stflag & PST_PROFIL) == 0) { 286 p->p_stflag |= PST_PROFIL; 287 /* 288 * This is only necessary if using the clock as the 289 * profiling source. 290 */ 291 if (++profprocs == 1 && stathz != 0) 292 psdiv = psratio; 293 } 294 } 295 296 /* 297 * Stop profiling on a process. 298 */ 299 void 300 stopprofclock(struct proc *p) 301 { 302 303 KASSERT(mutex_owned(&p->p_stmutex)); 304 305 if (p->p_stflag & PST_PROFIL) { 306 p->p_stflag &= ~PST_PROFIL; 307 /* 308 * This is only necessary if using the clock as the 309 * profiling source. 310 */ 311 if (--profprocs == 0 && stathz != 0) 312 psdiv = 1; 313 } 314 } 315 316 void 317 schedclock(struct lwp *l) 318 { 319 if ((l->l_flag & LW_IDLE) != 0) 320 return; 321 322 sched_schedclock(l); 323 } 324 325 /* 326 * Statistics clock. Grab profile sample, and if divider reaches 0, 327 * do process and kernel statistics. 328 */ 329 void 330 statclock(struct clockframe *frame) 331 { 332 #ifdef GPROF 333 struct gmonparam *g; 334 intptr_t i; 335 #endif 336 struct cpu_info *ci = curcpu(); 337 struct schedstate_percpu *spc = &ci->ci_schedstate; 338 struct proc *p; 339 struct lwp *l; 340 341 /* 342 * Notice changes in divisor frequency, and adjust clock 343 * frequency accordingly. 344 */ 345 if (spc->spc_psdiv != psdiv) { 346 spc->spc_psdiv = psdiv; 347 spc->spc_pscnt = psdiv; 348 if (psdiv == 1) { 349 setstatclockrate(stathz); 350 } else { 351 setstatclockrate(profhz); 352 } 353 } 354 l = ci->ci_onproc; 355 if ((l->l_flag & LW_IDLE) != 0) { 356 /* 357 * don't account idle lwps as swapper. 358 */ 359 p = NULL; 360 } else { 361 p = l->l_proc; 362 mutex_spin_enter(&p->p_stmutex); 363 } 364 365 if (CLKF_USERMODE(frame)) { 366 KASSERT(p != NULL); 367 if ((p->p_stflag & PST_PROFIL) && profsrc == PROFSRC_CLOCK) 368 addupc_intr(l, CLKF_PC(frame)); 369 if (--spc->spc_pscnt > 0) { 370 mutex_spin_exit(&p->p_stmutex); 371 return; 372 } 373 374 /* 375 * Came from user mode; CPU was in user state. 376 * If this process is being profiled record the tick. 377 */ 378 p->p_uticks++; 379 if (p->p_nice > NZERO) 380 spc->spc_cp_time[CP_NICE]++; 381 else 382 spc->spc_cp_time[CP_USER]++; 383 } else { 384 #ifdef GPROF 385 /* 386 * Kernel statistics are just like addupc_intr, only easier. 387 */ 388 g = &_gmonparam; 389 if (profsrc == PROFSRC_CLOCK && g->state == GMON_PROF_ON) { 390 i = CLKF_PC(frame) - g->lowpc; 391 if (i < g->textsize) { 392 i /= HISTFRACTION * sizeof(*g->kcount); 393 g->kcount[i]++; 394 } 395 } 396 #endif 397 #ifdef LWP_PC 398 if (p != NULL && profsrc == PROFSRC_CLOCK && 399 (p->p_stflag & PST_PROFIL)) { 400 addupc_intr(l, LWP_PC(l)); 401 } 402 #endif 403 if (--spc->spc_pscnt > 0) { 404 if (p != NULL) 405 mutex_spin_exit(&p->p_stmutex); 406 return; 407 } 408 /* 409 * Came from kernel mode, so we were: 410 * - handling an interrupt, 411 * - doing syscall or trap work on behalf of the current 412 * user process, or 413 * - spinning in the idle loop. 414 * Whichever it is, charge the time as appropriate. 415 * Note that we charge interrupts to the current process, 416 * regardless of whether they are ``for'' that process, 417 * so that we know how much of its real time was spent 418 * in ``non-process'' (i.e., interrupt) work. 419 */ 420 if (CLKF_INTR(frame) || (curlwp->l_pflag & LP_INTR) != 0) { 421 if (p != NULL) { 422 p->p_iticks++; 423 } 424 spc->spc_cp_time[CP_INTR]++; 425 } else if (p != NULL) { 426 p->p_sticks++; 427 spc->spc_cp_time[CP_SYS]++; 428 } else { 429 spc->spc_cp_time[CP_IDLE]++; 430 } 431 } 432 spc->spc_pscnt = psdiv; 433 434 if (p != NULL) { 435 atomic_inc_uint(&l->l_cpticks); 436 mutex_spin_exit(&p->p_stmutex); 437 } 438 439 #ifdef KDTRACE_HOOKS 440 cyclic_clock_func_t func = cyclic_clock_func[cpu_index(ci)]; 441 if (func) { 442 (*func)((struct clockframe *)frame); 443 } 444 #endif 445 } 446 447 /* 448 * sysctl helper routine for kern.clockrate. Assembles a struct on 449 * the fly to be returned to the caller. 450 */ 451 static int 452 sysctl_kern_clockrate(SYSCTLFN_ARGS) 453 { 454 struct clockinfo clkinfo; 455 struct sysctlnode node; 456 457 clkinfo.tick = tick; 458 clkinfo.tickadj = tickadj; 459 clkinfo.hz = hz; 460 clkinfo.profhz = profhz; 461 clkinfo.stathz = stathz ? stathz : hz; 462 463 node = *rnode; 464 node.sysctl_data = &clkinfo; 465 return (sysctl_lookup(SYSCTLFN_CALL(&node))); 466 } 467
Indexes created Thu Sep 25 16:09:42 GMT 2025